mecanum_drive_controller: Declare missing backward_ros dependency (backport #1941)

[mergify]

Since CMakeLists.txt contains "find_package(backward_ros REQUIRED)", without this change, compilation can fail with the following error:

CMake Error at CMakeLists.txt:25 (find_package):
  By not providing "Findbackward_ros.cmake" in CMAKE_MODULE_PATH this project
  has asked CMake to find a package configuration file provided by
  "backward_ros", but CMake did not find one.

This change fixes that.

---

This is an automatic backport of pull request #1941 done by Mergify.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.56%. Comparing base (3602fb4) to head (f4f1e1d).
⚠️ Report is 2 commits behind head on jazzy.

Additional details and impacted files

@@           Coverage Diff           @@
##            jazzy    #1943   +/-   ##
=======================================
  Coverage   85.55%   85.56%           
=======================================
  Files         138      138           
  Lines       13236    13235    -1     
  Branches     1146     1145    -1     
=======================================
  Hits        11324    11324           
  Misses       1550     1550           
+ Partials      362      361    -1     

Flag	Coverage Δ
unittests	85.56% <ø> (+<0.01%)	⬆️

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see 1 file with indirect coverage changes

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